Patient interface systems for ensuring effective seal

ABSTRACT

A patient interface system for delivering breathable gas to a patient includes a patient interface configured to sealingly engage the patient&#39;s face. A mechanism may be provided to ensure that an effective seal is maintained between the patient interface and the patient&#39;s face by preventing, reducing, minimizing or limiting effects of disruptive forces, such as tube drag, on the patient interface.

CROSS REFERENCE TO APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/214,132, filed Mar. 14, 2014, now U.S. Pat. No. 10,456,540, whichclaims the benefit of U.S. Provisional Application Ser. No. 61/798,900,filed Mar. 15, 2013, each of which is hereby incorporated herein byreference in its entirety.

FIELD OF TECHNOLOGY

The present invention relates to patient interfaces and patientinterface systems for delivering pressurized air to a patient (e.g., forrespiratory therapy), and in particular apparatuses and methods forensuring that an effective seal is maintained between the patientinterface and the patient's face.

BACKGROUND OF TECHNOLOGY

In respiratory therapy (e.g., treatment of Sleep Disordered Breathing(SDB) such as Obstructive Sleep Apnea (OSA) with Continuous PositiveAirway Pressure (CPAP) or Non-Invasive Positive Pressure Ventilation(NIPPV)) where breathable gas is delivered to a patient interface (e.g.,cushion, nasal “cradle,” etc.) under pressure, a good seal is typicallymaintained between the patient interface and the patient's face. Leaksbetween the patient interface and the patient's face can reduce theeffectiveness of, and compliance with, the therapy, as the prescribedtreatment parameters are not being maintained.

Leaks are especially prone to occur as the patient moves during thenight. Movement of and drag on the air delivery tube as the patientturns or moves can alter the positioning and alignment of the patientinterface with respect to the patient's face. This movement can betranslated or transferred to the seal formed between the patientinterface and the patient's face which may in turn create a leak in theseal. Thus, while the patient interface may initially be leak free whenattached to the patient, leaks are prone to develop later in the nightas the patient moves in bed which may cause the patient to wakenrendering the therapy ineffective.

In certain mask designs, air pressure from within a mask chamber (orpressure chamber) may act on the underside of a mask seal, e.g., a thinflap, to urge the flap into sealing position. However in other maskdesigns, this air pressure effect may not impact on the sealeffectiveness.

Accordingly, there is a continuous need in the art for patient interfacesystems, accessories, etc. that ensure a good seal between the patientinterface and the patient's face is maintained.

SUMMARY OF TECHNOLOGY

A first aspect of the disclosed technology relates to a patientinterface system configured to prevent or reduce deleterious effects ofdisruptive forces (e.g., tube drag) on the seal between a patientinterface and the patient's face.

Another aspect of the disclosed technology relates to an apparatusarranged to maintain a patient interface in sealing relation with apatient's face.

Another aspect of the disclosed technology relates to an apparatusconfigured to prevent, limit, minimize or reduce degradation of a sealbetween a patient interface and a patient's face.

Another aspect of the disclosed technology relates to an apparatusconfigured to absorb disruptive forces (e.g., tube drag) exerted on apatient interface.

Another aspect of the disclosed technology is a method and apparatus toimprove the robustness and/or effectiveness of a seal between a patientinterface and a patient's face when an air pressure effect acting on theunderside of a seal portion of the patient interface does not provide anadequate seal with the patient's face.

Another aspect of the disclosed technology is a patient interface havinga pressure chamber, and seal portion that is not supported by airpressure in use.

Another aspect of the disclosed technology is a patient interface havinga seal member with an interior surface and an exterior surface, andwherein a seal is formed in use with a portion of the interior surfaceof the seal member.

Another aspect of the disclosed technology relates to an apparatus forensuring an effective seal is maintained between a respiratory patientinterface and a patient's face, the respiratory patient interfaceadapted to receive pressurized gas from a supply tube and deliver thepressurized gas to the patient's airways, the patient interfaceincluding a seal portion adapted to seal against the patient's face. Theapparatus comprises a device having a lower portion operatively coupledto the supply tube and an upper portion disposed adjacent the sealportion of the patient interface, wherein movement of the supply tubecauses the device to urge the seal portion of the patient interfacetoward the patient's face.

Another aspect of the disclosed technology relates to an apparatus forpreventing leakage between a respiratory patient interface and apatient's face, where the respiratory patient interface is adapted toreceive pressurized gas from a supply tube and deliver the pressurizedgas to the patient's airways, and the patient interface includes leftand right portions adapted to seal against the patient's face. Theapparatus comprises first and second arms pivotally coupled to oneanother. The first and second arms each include lower portions coupledto the supply tube and upper portions disposed respectively adjacent theleft and right portions of the patient interface, wherein movement ofthe supply tube causes the first and second arms to urge the left andright portions of the patient interface toward the patient's face.

Another aspect of the disclosed technology relates to a patientinterface system for delivering pressurized gas to a patient's airways.The system comprises a supply tube to deliver a supply of pressurizedgas; a patient interface to receive the supply of pressurized gas fromthe supply tube and deliver the pressurized gas to the patient'sairways, the patient interface including left and right portions adaptedto seal against the patient's face; and a scissor mechanism includingfirst and second arms pivotally coupled to one another, the first andsecond arms each including lower portions coupled to the supply tube andupper portions disposed respectively adjacent the left and rightportions of the patient interface, wherein movement of the supply tubecauses the first and second arms to urge the left and right portions ofthe patient interface toward the patient's face.

Another aspect of the disclosed technology relates to a patientinterface system for delivering pressurized gas to a patient. The systemcomprises a patient interface adapted to sealingly communicate with thepatient's nose; and a support pad connected to the patient interface toat least partially support the patient interface on the patient's face,the support pad structured to rest on a nasal bridge region of thepatient's face, wherein the support pad is secured to the patient by atleast one first strap having a vector with a downward directionalcomponent or an adhesive that requires no straps.

Another aspect of the disclosed technology relates to a patientinterface for delivering pressurized gas to a patient. The patientinterface comprises a patient contacting side adapted to sealinglyengage the patient's face by a compressive force; a non-patientcontacting side opposite the patient contacting side; and a chamberextending from a seal-side portion on the patient contacting side to anon-seal side portion on the non-patient contacting side, the chamberincluding a fluid, wherein the fluid flows between the seal-side portionof the chamber and the non-seal side portion of the chamber inaccordance with a magnitude of the compressive force.

Another aspect of the disclosed technology relates to a patientinterface for delivering pressurized gas to a patient. The patientinterface comprises a patient contacting side adapted to sealinglyengage the patient's face by a compressive force; a non-patientcontacting side opposite the patient contacting side; and a chamberextending from a seal-side portion on the patient contacting side to anon-seal side portion on the non-patient contacting side, the chamberincluding a fluid, wherein the seal-side portion includes an innerelastic wall and an outer wall, and the inner wall elastically expandsas fluid flows from the non-seal side portion to the seal-side portion.

Another aspect of the disclosed technology relates to a method ofsealing a patient interface with a patient's face, the patient interfaceconfigured to deliver pressurized gas to the patient, the patientinterface comprising a patient contacting side adapted to sealinglyengage the patient's face, a non-patient contacting side opposite thepatient contacting side, and a fluid-filled chamber extending from aseal-side portion on the patient contacting side to a non-seal sideportion on the non-patient contacting side. The method comprisesengaging the patient contacting side of the patient interface with thepatient's face thereby applying a compressive force to the patientinterface; forming at least a partial seal between the patient interfaceand the patient's face; and expanding the seal-side portion of thechamber by causing fluid to flow from the non-seal side portion to theseal-side portion of the chamber in response to a decrease in thecompressive force.

Another aspect of the disclosed technology relates to a patientinterface system for delivering pressurized gas to a patient. The systemcomprises a patient interface adapted to seal against the patient'sface; a frame element to at least partially support the patientinterface on the patient's face; and at least one resilient memberdisposed between the patient interface and the frame element to urge thepatient interface against the patient's face.

Another aspect of the disclosed technology relates to a patientinterface system for delivering pressurized gas to a patient. The systemcomprises a patient interface including first and second side portionsadapted to seal against the patient's face; and at least one resilientmember coupled to the patient interface and configured to absorb adisruptive force thereby preventing degradation of the seal against thepatient's face.

Another aspect of the disclosed technology relates to a patientinterface system for delivering pressurized gas to a patient. The systemcomprises a patient interface including a seal portion configured tosealingly engage the patient's face; and a device coupled to the sealportion and arranged to exert a force against the seal portion to urgethe seal portion against the patient's face in response to a disruptiveforce exerted on the seal portion.

Still another aspect of the disclosed technology relates to a patientinterface system for delivering pressurized gas to a patient. The systemcomprises a patient interface including seal means configured forsealingly engaging the patient's face; and seal maintaining means forexerting a force against the seal means to urge the seal means againstthe patient's face in response to a disruptive force exerted on the sealmeans.

Other aspects, features, and advantages of this technology will becomeapparent from the following detailed description when taken inconjunction with the accompanying drawings, which are a part of thisdisclosure and which illustrate, by way of example, principles of thisinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings facilitate an understanding of the variousembodiments of this technology. In such drawings:

FIGS. 1-1 and 1-2 are schematic representations of a patient interfacesystem according to an example of the disclosed technology;

FIG. 2-1 is a perspective view of a patient interface system accordingto another example of the disclosed technology;

FIG. 2-2 is a front view of the patient interface system of FIG. 2-1;

FIG. 2-3 is a side view of the patient interface system of FIG. 2-1;

FIG. 3-1 is a perspective view of patient interface according to anotherexample of the disclosed technology;

FIG. 3-2 is a side view of the patient interface of FIG. 3-1;

FIG. 3-3 is a cross-sectional view along the line 3-3-3-3 in FIG. 3-2;

FIG. 3-4 is a cross-sectional view of the patient interface of FIG. 3-1showing movement of fluid from a non-seal side portion to a seal-sideportion of the chamber;

FIG. 4-1 is a front perspective view of a patient interface systemaccording to another example of the disclosed technology;

FIG. 4-2 is a schematic representation of the patient interface systemof FIG. 4-1;

FIG. 4-3 is a schematic representation of the patient interface systemof FIG. 4-1 in response to a disruptive force against the patientinterface system;

FIG. 5-1 is a front perspective view of a patient interface systemaccording to another example of the disclosed technology;

FIG. 5-2 is a schematic representation of the patient interface systemof FIG. 5-1; and

FIG. 5-3 is a schematic representation of the patient interface systemof FIG. 5-1 in response to a disruptive force against the patientinterface system.

DETAILED DESCRIPTION OF ILLUSTRATED EXAMPLES

The following description is provided in relation to several exampleswhich may share common characteristics and features. It is to beunderstood that one or more features of any one example may becombinable with one or more features of the other examples. In addition,any single feature or combination of features in any of the examples mayconstitute an additional example or examples.

In this specification, the word “comprising” is to be understood in its“open” sense, that is, in the sense of “including”, and thus not limitedto its “closed” sense, that is the sense of “consisting only of”. Acorresponding meaning is to be attributed to the corresponding words“comprise”, “comprised” and “comprises” where they appear.

1. Patient Interface Systems

In treatment of SDB (e.g., by pneumatically splinting the patient'sairways with gas or air pressurized in the range of about 2-30 cm H₂O(typically 8-12 cm H₂O)), a variety of patient interfaces may be used todeliver the breathable gas to the patient's airways. As an example,suitable patient interfaces may include nasal and/or oral cushions,nasal “cradles,” nasal “pillows,” nasal prongs, nozzles, and cannulae.An interior area of the patient interface defined by the seal betweenthe patient and the patient interface may be considered a pressurechamber. As mentioned above, to ensure effective therapy, a good sealbetween the patient interface and the patient should be maintained.

Thus, the patient interface system should be designed to avoid leakagethat causes annoyance and/or discomfort to the patient and to improvethe quality of the therapy by reducing or eliminating problemsassociated with leakage.

As the patient moves during the night, disruptive forces such as tubedrag are transferred to the patient interface tending to cause thepositioning of the patient interface to become altered, therebyincreasing the likelihood that the seal will leak. Patient interfacesystems according to examples of the disclosed technology may bedesigned with various seal maintenance structures (described below) toprevent, reduce or stop such leakage from the patient interface. Thepatient interface systems may also be designed to reduce or eliminatenoise disturbance to the patient, which may be a consequence of aleaking seal.

It is noted that features described herein for preventing or reducingleakage described in relation to a particular patient interface may alsobe useable with a different patient interface.

2. Scissor Mechanism

Referring to FIG. 1, a patient interface system includes a nasal cradle101 and a seal maintenance device 110 to prevent movement of a supplytube 150 from disrupting the seal with the patient's face. The nasalcradle 101 is placed at an entrance to the patient's nares, resting onan upper lip region of the patient's face. The nasal cradle isstructured to form an interface with the nares and includes right andleft 102, 104 portions (seal portions) (from the patient's perspectivewhen the patient interface worn) that seal with the sides of thepatient's nose, or the external nares. The supply tube 150 is coupled tothe nasal cradle 101 and is arranged to deliver breathable gas to thepatient. Headgear 170 may aid is supporting the cradle 101 on thepatient's face.

The seal maintenance device 110 includes an actuator 160 coupled to thesupply tube 150, an extensible connector 162 connecting the actuator 160and the cradle 101, first and second scissor arms 112, 114 havingrespective upper portions 112(1), 114(1) coupled to the cradle 101 andrespective lower portions 112(2), 114(2) coupled to the actuator 160,and a support member 164 for pivotably supporting the first and secondscissor arms 112, 114. The seal maintenance device 110 may be coupled tothe supply tube 150 such that a downward (or any other direction tendingto pull the tube away from the patient's face) force (e.g., caused bytube drag) on the tube 150 is transferred to the seal maintenance device110 to prevent the force from causing leakage at the seal.

The support member 164 is connected to or otherwise anchored by theheadgear 170. In an example, the support member 164 may form part of theheadgear 170. The extensible connector 162 has a first end 162(1)connected to the support member 164 and a second end 162(2) connected tothe actuator 160. When a disruptive force f1 is applied to the supplytube 150, the actuator exerts a force on the second end 162(2) of theextensible connector 162. As a result, the extensible connector 162extends its length in the direction of arrow A due to its extensibleconstruction and the connection of the first end 162 (1) to the supportmember 164. That is, the first end 162(1) of the extensible connector162 is anchored via its connection to the support member 164 which is inturn connected to headgear 170 which is securely fastened to thepatient's head. The pivot 116 of the scissor arms 112, 114 is alsoconnected to the support member 164. The support member 164 may beformed of a substantially rigid material (e.g., metal, hard plastic,etc.).

The extensible connector 162 is constructed in a manner that allows itto extend its length so as to be movable from a compressed positioned toan extended position. Such movement of the extensible connector 162effectively decouples movement of the supply tube 150 from the cradle101. As such, transference of the force f1 to the cradle 101 isminimized or even completely eliminated. In the illustrated example, theextensible connector 162 will retract to the compressed position, shownin FIG. 1-1, when no external force is applied which would cause theextensible connector 162 to extend. In an example, the extensibleconnector 162 may include rigid portions 162(3) and flexible portions162(4) such that the flexible portions may tend to fold when theextensible connector 162 is compressed and stretch out when theextensible connector is extended.

The actuator 160 is connected to the second end 162(2) of the extensibleconnector 162. Thus, when the disruptive force f1 is applied, theactuator 160 moves away from the cradle 101 along with the supply tube150 and the extensible connector 162. The actuator may include a pair ofslots 132, 134 formed therein and configured to respectively receive thelower portions 112(2), 114(2) of the first and second scissor arms 112,114. The slots 132, 134 may be curved or angled such that proximal endsof the slots (with respect to the patient) are disposed inwardly ofdistal ends of the slots. As such, movement of the actuator 160 awayfrom the patient will cause the lower portions 112(2), 114(2) of thescissor arms to move closer (inwardly) to one another, in the directionof arrows B. Such inward movement of the lower portions 112(2), 114(2)of the scissor arms 112, 114 causes the upper portions 112(1), 114(1) ofthe scissor arms to swing towards one another. This motion causes theupper portions 112(1), 114(1) to exert a force on the right and leftportions 102, 104 of the nasal cradle 101 to urge the right and leftportions 102, 104 against the patient's face, in the direction of arrowsC. The upper portions 112(1), 114(1) of the scissor arms may cause theright and left portions 102, 104 of the cradle 101 to stretch lengthwiseas well as move inwardly, as shown by the direction of the arrows C. Byconverting motion of the supply tube 150 away from the patient's faceinto motion of the seal maintenance device 110 which actually urges thenasal cradle 101 towards the patient's face, deleterious effects of tubedrag and other disruptive forces can be overcome and a good seal can bemaintained as the patient moves during the night.

The upper portions 112(1), 114(1) may be respectively pivotablyconnected (e.g., via connectors 122, 124) to the right and left portions102, 104 of the cradle 101. Connectors 122, 124 may be attached to thecradle and include a portion pivotably connected to the upper portions112(1), 114(1) of the scissor arms. Such pivotal connection may be abouta single axis, two axes, or more than two axes (e.g., a ball and socketjoint).

The actuator 160 may provide a swivel connection to the supply tube 150.The first and second scissor arms 112, 114 may be constructed of a rigidor semi-rigid material such as nylon, polypropylene, polycarbonate, orsilicone having a Shore A hardness with the range of 30-90, preferably40-70, for example. The actuator 160 may be formed of a substantiallyrigid material (e.g., metal, hard plastic, etc.)

3. Support Pad

Referring to FIGS. 2-1 to 2-3, a patient interface system includes anasal cradle 201 and a support pad 220 to help stabilize the cradle andto prevent movement of a supply tube from disrupting the seal with thepatient's face. Similar to the nasal cradle 101 described above, thenasal cradle 201 is placed at an entrance to the patient's nares,resting on an upper lip region of the patient's face. The nasal cradleis structured to form an interface with the nares and includes right andleft 202, 204 portions (seal portions) that seal with the sides of thepatient's nose, or the external nares. A supply tube (not shown)connects to the nasal cradle 201 to provide a supply of gas.

A connecting member 235 extends over the tip of nose region andinterconnects the nasal cradle 201 and the support pad 220 which ispositioned generally over the nasal bridge region of the patient's face.The support pad 220 and/or the connecting member 235 may be made from arigid material, a flexible material, or a combination of rigid andflexible materials. Suitable materials for the support pad andconnecting member may include a silicone, polyurethane, adhesive backedcotton or textile. The support pad 220 and/or the connecting member 235may have a relatively high friction coefficient to limit downwardsmovement along the patient's nose.

Upper straps may be connected to the right and left portions 202, 204 ofthe nasal cradle to support the nasal cradle 201, particularly the topof lip and under the nose region of the cradle. The upper straps extendupwardly at an angle α within the range of 30-60°, preferably 45°, withrespect to the horizontal axis X. V1 represents vectors for the upperstraps and indicates the direction of force applied to the nasal cradleby the straps. The upper straps may enhance the seal at the sides of thepatient's nose by pulling the nasal cradle 201 into close conformancewith the curvature of the patient's nose.

Lower straps may be connected to the right and left portions 202, 204 ofthe support pad 220 to stabilize the tip of nose region of the cradle201, particularly when a disruptive force such as tube drag istransferred to the cradle. The lower straps extend downwardly at anangle θ within the range of 30-60°, preferably 45°, with respect to thehorizontal axis X. V2 represent vectors for the lower straps andindicates the direction of force applied to the support pad 220 by thestraps.

The support pad 220 and system of upper and lower straps function tosupport and stabilize the nasal cradle 201 such that in the event of adisruptive force, such as tube drag, the nasal cradle may be securelyheld against the patient's face to prevent or minimize leakage at theseal.

In another example, instead of the nasal cradle 201, a different patientinterface may be used, e.g., a pair of nasal pillows, such that theconnecting member 235 extends over the tip of nose region andinterconnects the nasal pillows and the support pad 220.

4. Fluid Chamber

Referring now to FIGS. 3-1 to 3-4, a cushion 300 is shown. In theillustrated example, the cushion 300 is a nasal cushion configured toengage the patient's nose, although other cushion types may be used. Thecushion 300 includes a non-face-contacting side 312 and aface-contacting side 314. The non-face-contacting side 312 is connectedto a connecting member 305 which provides a supply of breathable gas tothe cushion 300. The connecting member 305 may be a supply tube, aconnector (such as a swivel connector or ball and socket type connector)interconnecting the cushion and a supply tube, or any other appropriatemechanism to introduce the breathable gas to the cushion. The breathablegas is communicated to the patient by an aperture 319 via a channel 321extending through the cushion 300. Suitable materials for the cushion300 include Silicone, polyurethane, rubber and textiles.

The cushion 300 includes a compressible interior fluid chamber and thusforms a compression or gasket-type seal with the patient's face. Thechamber 320 may be filled with any fluid (e.g., gas, liquid) or gel aslong as they are flowable. The cushion 300 relies on its softness andcompliance, through compression of the fluid chamber 320, in a directionnormal to the patient's face to conform to the patient's facial anatomy.

As shown in FIG. 3-3, the fluid chamber 320 extends from thenon-face-contacting side 312 to the face-contacting side 314 of thecushion. The chamber 320 has a non-seal side portion 322 on thenon-face-contacting side 312 of the cushion and a seal-side portion 324on the face-contacting side 314 of the cushion. The aperture 319 isdelimited by an inner wall having a first (lower) inner wall portion 332on the non-face-contacting side 312 of the cushion and a second (upper)inner wall portion 334 on the face-contacting side 314 of the cushion.The inner wall is joined to an outer wall having a first (lower) outerwall portion 342 on the non-face-contacting side 312 of the cushion anda second (upper) outer wall portion 344 on the face-contacting side 314of the cushion. The face-contacting side 314 (e.g., second inner wallportion 334) of the cushion forms a seal portion that seals with thepatient's face (e.g., nose, e.g., sides of the patient's nose, or theexternal nares).

The second inner wall portion 334 is relatively thin as compared to thefirst inner wall portion 332 which has a thicker cross-section. Thethinner arrangement of the second inner wall portion 334 allows forbetter conformance to the patient's face. This arrangement also allowsthe second inner wall portion 334 to elastically expand and contract asfluid (or gel) in the chamber 320 flows to and from the seal-sideportion 324 of the chamber 320.

The first outer wall portion 342 is relatively thin as compared to thesecond outer wall portion 344 which has a thicker cross-section. Thesecond outer wall portion 344 forms an outer wall of the seal-sideportion 324 of the chamber 320. The thicker second outer wall portion344 resists distortion and forms a stable base which allows the thinnersecond inner wall portion 334 to expand and contract when fluid flows toand from the seal-side portion 324 of the chamber. That is, the secondinner wall portion 334 is thinner than the second outer wall portion 344to encourage the second inner wall portion 334 to expand and conform tothe patient's face to create an effective seal as the fluid or gel flowsinto the seal-side portion 324 of the chamber 320.

Similarly, the thicker first inner wall portion 332 resists distortionand forms a stable base which allows the thinner first outer wallportion 342 to elastically expand and contract when fluid flows to andfrom the non-seal side portion 322 of the chamber 320. Morespecifically, occlusion of the channel 321 is prevented by the thickerfirst inner wall portion 332 which resists distortion and expansion asthe fluid or gel flows into the non-seal side portion 322 of the chamber320.

In use, as the patient's face is pressed against the face-contactingside 314 of the cushion 300 (e.g., as a result of headgear holding thecushion against the patient's face), the seal-side portion 324 of thechamber compresses and the second inner wall portion 334 conforms to thepatient's face to form a seal therewith. Compression of the seal-sideportion 324 of the chamber 320 causes the fluid or gel to shift towardthe non-seal side portion 322 of the chamber. Fluid flow into thenon-seal side portion 322 causes the first outer wall 342 to expandelastically. If, for example, the force applied by the headgear isreduced, or a disruptive force such as tube drag displaces the cushion,the first outer wall portion 342 will contract to force fluid in thedirection of arrows 360 toward the seal-side portion 324 of the chamber.As a result, the seal-side portion 324 expands (via elastic expansion ofthe second inner wall portion 334), increasing the thickness or heightof the face-contacting side 314 of the cushion to fill any gap (betweenthe patient's face and the cushion) caused by the displacement, as shownin FIG. 3-4.

5. Spring Support

FIGS. 4-1 to 4-3 show a patient interface system including a nasalcradle 400 and a resilient member to support the nasal cradle in sealingengagement with the patient's face. The nasal cradle 400 is structuredto form an interface with the nares and includes right and left portions402, 404 (seal portions) that seal with the sides of the patient's nose,or the external nares. The resilient member may be arranged to passivelycounteract disruptive forces (e.g., tube drag) and thereby maintain aneffective seal. That is, the resilient member may be configured toabsorb a disruptive force thereby preventing degradation of the sealagainst the patient's face. Additionally, or alternatively, theresilient member may be configured to urge the seal portion against thepatient's face in response to a disruptive force exerted on the sealportion.

The resilient member may comprise one or more springs, such as amechanical spring. In another example, the resilient member may be aflexible beam, e.g., that is configured to bend. The resilient membermay also be a compressible member. The resilient member may beconstructed from an elastomeric material. The resilient member may beconstructed from a foam, e.g., an elastic foam, and/or a visco-elasticfoam. In the illustrated example, the patient interface system includessprings 432, 434.

In an example, the patient interface system may include an optionalbow-shaped elastic member 420 which extends around the cradle 400 andincludes right and left sides 422, 424 connected respectively to theright and left portions 402, 404 of the cradle. A supply tube 460 isconnected to the frame 440 and is in fluid communication with an inlet462 of the elastic member 420 or the cradle 400 to provide breathablegas to the patient's airways via the nasal cradle. A middle portion 426of the elastic member 420 or the cradle 400 is connected to a frame atan engaging portion 443 of the frame. The middle portion 426 may beseated in the frame 440, which may have a concave shape, or otherwiseengaged with the frame which provides a rigid support for the nasalcradle 400 and/or the elastic member 420. The frame 440 is connected toheadgear 450 at its ends.

As mentioned above, the elastic member 420 may be omitted and thesprings 432, 434 may be connected directly to the right and leftportions 402, 404 of the nasal cradle 400.

The spring 432, (e.g., a compression spring), is disposed between theright side 422 of the elastic member (or right and left portions of thenasal cradle) and a corresponding portion of the frame 440. Likewise,the spring 434 is disposed between the left side 424 of the elasticmember and a corresponding portion of the frame. The springs 432, 434are compressed when the nasal cradle 400 is positioned on the patient'sface. As such, the springs exert outward forces f_(c) against both theframe 440 and the right and left 422, 424 sides of the elastic member420 (or the right and left portions 402, 404 of the nasal cradle 400 ifconnected directly thereto). Since the frame is a sturdy, rigid orsemi-rigid member, the springs 432, 434 tend to push the right and left402, 404 portions of the nasal cradle against the patient's nose whichaids in establishing a good seal.

In use, springs 432, 434 are in compression. Thus, if a disruptive forcef3 such as tube drag acts to pull the frame 440, the elastic member 420,or the cradle 400 away from the patient's nose, the springs 432, 434will resist such movement of the elastic member 420 or nasal cradle 400,thus effectively decoupling the cradle 400 from the frame 440 and thesupply tube 460, as shown in FIGS. 4-2 and 4-3. In response to thedisruptive force f3, the springs may extend, for example as shown withregard to spring 432 in FIG. 4-3. Although the spring 432 extends (ispartially unloaded) in response to the disruptive force f3, the spring432 remains in compression. Therefore, spring 432 continues to exertforce f_(c) against the right portion 402 of the nasal cradle. In theillustrated example, since disruptive force f3 is exerted on the rightside of the nasal cradle, while spring 432 is partially unloaded, spring434 may be further loaded thereby also remaining in compression. Assuch, the patient interface system may exhibit an increased ability toovercome such disruptive forces and prevent or limit degradation of theseal since the springs 432, 434 remain in compression at all timesthereby ensuring an outward force f_(c) by the springs pushes the nasalcradle towards the patient's face to maintain a good seal even when adisruptive force is exerted on the patient interface.

Springs 432, 434 may be formed of resilient metals (e.g., spring steel).Springs 432, 434 may also be formed of a resilient thermoplasticmaterial.

In another example, an air pocket is disposed between the frame 440 andthe nasal cradle in place of the springs 432, 434. The air pocket wouldresist compression and therefore in the event of a disruptive force suchas tube drag, would exert a force tending to push the nasal cradleagainst the patient's nose. Other materials, such as silicone, metal,plastic and gel may be used to function as a spring.

It is also noted that the springs may be disposed at different locationsalong the nasal cradle to stabilize the seal in that region (e.g., nosetip region).

Further, instead of the nasal cradle 400, a different patient interfacemay be used, e.g., a pair of nasal pillows, such that the springs 432,434 are positioned between a frame member and the nasal pillows to urgethe nasal pillows into sealing engagement with the patient's nares, asshown in FIGS. 5-1 to 5-3. Referring to FIG. 5-1, springs 432, 434 maybe disposed between the frame 440 and a support member 520 whichsupports a pair of nasal pillows 502, 504. The nasal pillows eachinclude a conical portion 512, 514 (seal portions) supported by arespective stem portion 522, 524. Each of the conical portions 512, 514includes a surface that seals against surfaces of the patient's nosesurrounding the nares. Springs 432, 434 function in the manner describedabove in relation to FIGS. 4-1 to 4-3 to maintain the nasal pillows 502,504 in sealing engagement with the patient's face even when a disruptiveforce is exerted on the patient interface.

While the technology has been described in connection with severalexamples, it is to be understood that the technology is not to belimited to the disclosed examples, but on the contrary, is intended tocover various modifications and equivalent arrangements included withinthe spirit and scope of the technology. Also, the various examplesdescribed above may be implemented in conjunction with other examples,e.g., one or more aspects of one example may be combined with one ormore aspects of another example to realize yet other examples. Further,each independent feature or component of any given assembly mayconstitute an additional example. In addition, while the technology hasparticular application to patients who suffer from OSA, it is to beappreciated that patients who suffer from other illnesses (e.g.,congestive heart failure, diabetes, morbid obesity, stroke, bariatricsurgery, etc.) can derive benefit from the above teachings. Moreover,the above teachings have applicability with patients and non-patientsalike in non-medical applications.

PARTS LIST

-   101 Nasal cradle-   102 Right portion of nasal cradle-   104 Left portion of nasal cradle-   110 Seal maintenance device-   112 First scissor arm-   112(1) Upper portion-   112(2) Lower portion-   114 Second scissor arm-   114(1) Upper portion-   114(2) Lower portion-   116 Pivot-   122 Connector-   124 Connector-   132 Slot-   134 Slot-   150 Supply tube-   160 Actuator-   162 Extensible connector-   162(1) First end of extensible connector-   162(2) Second end of extensible connector-   162(3) Rigid portions-   162(4) Flexible portions-   164 Support member-   170 Headgear-   201 Nasal cradle-   202 Right portion of nasal cradle-   204 Left portion of nasal cradle-   220 Support pad-   222 Right portion of support pad-   224 Left portion of support pad-   235 Connecting member-   f1 Force-   f2 Force-   f3 Force-   f_(c) Force-   V1 First vector-   V2 Second vector-   X Axis-   300 Nasal cushion-   305 Connecting member-   312 Non-face-contacting side-   314 Face-contacting side-   319 Aperture-   320 Fluid chamber-   321 Channel-   322 Non-seal side portion of chamber-   324 Seal-side portion of chamber-   332 First inner wall portion-   334 Second inner wall portion-   342 First outer wall portion-   344 Second outer wall portion-   360 Arrows-   400 Nasal cradle-   402 Right portion of nasal cradle-   404 Left portion of nasal cradle-   420 Elastic member-   422 Right side of elastic member-   424 Left side of elastic member-   426 Middle portion of elastic member-   432 Spring-   434 Spring-   440 Frame-   443 Engaging portion-   450 Headgear-   460 Supply tube-   462 Inlet-   502 Nasal pillow-   504 Nasal pillow-   512 Conical portion-   514 Conical portion-   520 Support member-   522 Stem portion-   524 Stem portion

What is claimed is:
 1. A patient interface for delivering pressurizedgas to a patient, comprising: a patient contacting side of the patientinterface adapted to, in use, sealingly engage the patient's face by acompressive force; a non-patient contacting side opposite the patientcontacting side; and a chamber extending from a seal-side portion on thepatient contacting side to a non-seal side portion on the non-patientcontacting side, the chamber including a predetermined amount of fluid,wherein, in use, the fluid flows between the seal-side portion of thechamber and the non-seal side portion of the chamber in accordance witha magnitude of the compressive force, wherein the seal-side portionincludes an upper inner wall and an upper outer wall, the upper innerwall being configured to directly contact the patient's face in use,wherein the upper inner wall has a thickness that is smaller than athickness of the upper outer wall to facilitate the flow of the fluidbetween the seal-side portion of the chamber and the non-seal sideportion of the chamber, and wherein the non-seal side portion includes alower inner wall, and wherein the upper inner wall forms a continuouswall structure with the lower inner wall, the upper inner wall and thelower inner wall being formed of a same material.
 2. The patientinterface of claim 1, wherein a material of the upper inner wall iselastic and is configured to elastically expand as fluid flows from thenon-seal side portion to the seal-side portion.
 3. The patient interfaceof claim 1, wherein the non-seal side portion includes a lower outerwall comprising a material that is elastic, and the lower outer wall ofthe non-seal side portion is configured to elastically expand as fluidflows from the seal-side portion to the non-seal side portion.
 4. Thepatient interface of claim 3, wherein the lower outer wall of thenon-seal side portion has a thickness that is smaller than a thicknessof the lower inner wall of the non-seal side portion.
 5. The patientinterface of claim 1, wherein fluid flows from the non-seal side portionto the seal-side portion when the magnitude of the compressive forcedecreases.
 6. The patient interface claim 1, wherein the patientinterface is a nasal cushion.
 7. The patient interface of claim 1,wherein the fluid is flowable.
 8. The patient interface of claim 1,wherein an aperture is formed through the patient interface tocommunicate the pressurized gas to the patient.
 9. The patient interfaceof claim 1, wherein the smaller thickness of the upper inner wallprovides the upper inner wall with increased flexibility as compared tothe upper outer wall to facilitate expansion and contraction of theseal-side portion of the chamber as the fluid flows between theseal-side portion of the chamber and the non-seal side portion of thechamber.
 10. A patient interface for delivering pressurized gas to apatient, comprising: a patient contacting side of the patient interfaceadapted to, in use, sealingly engage the patient's face by a compressiveforce; a non-patient contacting side opposite the patient contactingside; and a chamber extending from a seal-side portion on the patientcontacting side to a non-seal side portion on the non-patient contactingside, the chamber including a predetermined amount of fluid, wherein thefluid flows between the seal-side portion of the chamber and thenon-seal side portion of the chamber in accordance with a magnitude ofthe compressive force, wherein the seal-side portion includes an upperinner wall and an upper outer wall, the upper inner wall comprising amaterial that is elastic, wherein, in use, the material of the upperinner wall is configured to elastically expand as fluid flows from thenon-seal side portion to the seal-side portion, wherein the non-sealside portion includes a lower inner wall and a lower outer wall, thelower outer wall comprising a material that is elastic, and wherein theupper inner wall forms a continuous wall structure with the lower innerwall, the upper inner wall and the lower inner wall being formed of asame material.
 11. The patient interface of claim 10, wherein fluidflows from the non-seal side portion to the seal-side portion when themagnitude of the compressive force decreases.
 12. The patient interfaceof claim 10, wherein the upper inner wall has a thickness that issmaller than a thickness of the upper outer wall.
 13. The patientinterface of claim 10, wherein, in use, the material of the lower outerwall of the non-seal side portion is configured to elastically expand asfluid flows from the seal-side portion to the non-seal side portion. 14.The patient interface of claim 13, wherein the lower outer wall of thenon-seal side portion has a thickness that is smaller than a thicknessof the lower inner wall of the non-seal side portion to facilitateelastic expansion of the lower outer wall of the non-seal side portionof the chamber.
 15. The patient interface of claim 10, wherein thepatient interface is a nasal cushion.
 16. The patient interface of claim10, wherein the fluid is flowable.
 17. The patient interface of claim10, wherein an aperture is formed through the patient interface tocommunicate the pressurized gas to the patient.
 18. The patientinterface of claim 10, wherein, in use, the material of the upper innerwall is configured to elastically expand and contract as fluid flows toand from the seal-side portion of the chamber.
 19. A method of sealing apatient interface with a patient's face, the patient interfaceconfigured to deliver pressurized gas to the patient, the patientinterface comprising a patient contacting side adapted to sealinglyengage the patient's face, a non-patient contacting side opposite thepatient contacting side, and a chamber filled with a predeterminedamount of fluid that extends from a seal-side portion of the chamber onthe patient contacting side of the patient interface to a non-seal sideportion of the chamber on the non-patient contacting side of the patientinterface, the method comprising: engaging the patient contacting sideof the patient interface with the patient's face thereby applying acompressive force to the patient interface; forming at least a partialseal between the patient interface and the patient's face; and expandingthe seal-side portion of the chamber by causing fluid to flow from thenon-seal side portion to the seal-side portion of the chamber inresponse to a decrease in the compressive force, wherein the seal-sideportion includes an upper inner wall and an upper outer wall, the upperinner wall comprising a material that is elastic, wherein, in use, thematerial of the upper inner wall is configured to elastically expand asfluid flows from the non-seal side portion to the seal-side portion,wherein the non-seal side portion includes a lower inner wall and alower outer wall, the lower outer wall comprising a material that iselastic, and wherein the upper inner wall forms a continuous wallstructure with the lower inner wall, the upper inner wall and the lowerinner wall being formed of a same material.
 20. The method of claim 19,wherein an amount of fluid that flows to the seal-side portion of thechamber is in accordance with a magnitude of the decrease in compressiveforce.
 21. The method of claim 19, wherein the upper inner wall has athickness that is smaller than a thickness of the upper outer wall. 22.The method of claim 19, wherein the material of the lower outer wall ofthe non-seal side portion is configured to contract as fluid flows fromthe non-seal side portion to the seal side portion.
 23. The method ofclaim 22, wherein the lower outer wall of the non-seal side portion hasa thickness that is smaller than a thickness of the lower inner wall ofthe non-seal side portion.
 24. The method of claim 19, wherein patientinterface is a nasal cushion.
 25. The method of claim 19, wherein thefluid is flowable.
 26. The method of claim 19, wherein, in use, thematerial of the upper inner wall is configured to elastically expand andcontract as fluid flows to and from the seal-side portion of thechamber.